Quan Chi may zone better, but overall Tanya is a better character. In fact, Tanya is arguably one of the best characters in the game, and I have a feeling a couple of Tanya players will do some serious damage this weekend at CEO. Pyromancer Tanya excels at a handful of gameplay aspects, which includes defense, footsies, punishing, zoning, and anti-zoning, but she is defined by her mobility. Mobility, backward mobility in particular, costs stamina in this game. In general, stamina governs various aspects of the game (i.e., forward and backward movement, pressure and combos for many characters). Using instant aerial teleport, Tanya maneuvers around the screen free of stamina. She is the only character in the game who is able to move even after combo breaking, which is a huge difference maker.
I personally think the invincibility on the teleport has to go. At EVO, we are going to see mirror matches of two players constantly teleporting and being unable to hit each other.